Abstract

Light emission from the junction of a scanning tunneling microscope (STM) is examined in the presence of 20 nm topographical features in thin gold films. These features significantly modify the emission rates of the junction. Contributions to this modification are discriminated by examining emission rates on samples where the material is varied spatially. It is found that the variability in STM photoemission rates between a gold tip and a gold sample under ambient conditions is due to the modification of localized gap plasmon modes and not to the presence of an electroluminescent gold cluster on the STM probe apex.

D. W. Lynch and W. R. Hunter, “Comments on the optical constants of metals and an introduction to the data for several metals,” in Handbook of Optical Constants of Solids,E. D. Palik, ed. (Academic, 1998), pp. 275–367.

Hunter, W. R.

D. W. Lynch and W. R. Hunter, “Comments on the optical constants of metals and an introduction to the data for several metals,” in Handbook of Optical Constants of Solids,E. D. Palik, ed. (Academic, 1998), pp. 275–367.

Lindquist, N. C.

Lynch, D. W.

D. W. Lynch and W. R. Hunter, “Comments on the optical constants of metals and an introduction to the data for several metals,” in Handbook of Optical Constants of Solids,E. D. Palik, ed. (Academic, 1998), pp. 275–367.

Other (1)

D. W. Lynch and W. R. Hunter, “Comments on the optical constants of metals and an introduction to the data for several metals,” in Handbook of Optical Constants of Solids,E. D. Palik, ed. (Academic, 1998), pp. 275–367.

Figures (4)

(a) and (c) Simultaneous photoemission and topographical maps of a 3×3 micron area on sample type A. The map in (a) has been scaled logarithmically. The map given in (c) has been filtered such that the mean topographical height value of each line in the raw image has been subtracted individually to provide contrast between the bulk film and the embedded particle regions. (b) Photoemission-counts cross-section along the dashed line in a 3×3 point moving average of (a). (d) Topography cross-section along the dashed line in an un-filtered version of (c). The bright regions in (c) correspond to apparent locations of Au particles. The STM parameters were as follows: Vs = 2.25V, I = 1nA, sampling time per point was 30ms. Scan resolution was 128×128 points.

(a) Simultaneous photoemission(top) and topographical(bottom) maps of a 1×1 micron area on sample type B. (b) Photoemission-counts cross-section along the dashed line in a 3×3 point moving average of (a,top). (c) Topography cross-section along the dashed line in (a,bottom). The triangular regions in (a,top) correspond to apparent positions of Au as deposited in a Fischer pattern in the sample. The remaining regions in (a,top) correspond to Pt. The STM parameters were as follows: Vs = 2.1 V, I = 0.7 nA, sampling time per point was 8ms. Scan resolution was 256×256 points.

(a) Simultaneous photoemission(top) and topographical(bottom) maps of a 3×3 micron area on sample type C. (b) Photoemission-counts cross-section along the dashed line in a 3×3 point moving average of (a,top). (c) Topography cross-section along the dashed line in (a,bottom). The lighter regions in (a,bottom) correspond to apparent positions of Au as deposited in a Fischer pattern in the sample where the spheres were not closely packed. The remaining regions in (a,bottom) correspond to ITO. The STM parameters were as follows: Vs = 2.0 V, I = 0.6 nA, sampling time per point was 15ms. Scan resolution was 128×128 points.